Officer Krystal Rivera was excited to celebrate her daughter's 11th birthday this weekend. But Rivera's life was tragically cut short late Thursday, when she was fatally shot in the back by a bullet fired by another officer.

Chicago police are investigating how a police officer was shot and killed while conducting an investigatory stop in Chatham Thursday night.

The officer, a 36-year-old woman and mother of a young daughter, was killed during a foot pursuit, according to Police Superintendent Larry Snelling.